📶 无线网络：看不见的网线📶 Wireless: Invisible Cables

上一片里，路由器把包裹送到家门口。可手机没插网线，怎么收到包裹？💻 小电脑拔掉网线，换乘看不见的电波去送货。 Last leaf, the router brought parcels to your front door. But your phone has no cable — how do its parcels arrive? 💻 The little computer unplugs the cable and delivers by invisible radio waves.

第 1 步：电波是看不见的网线Step 1: Waves are invisible cables

💻 小电脑站在路由器旁，看它发出一圈圈电波。💻 The little computer watches the router send out ring after ring of waves.

路由器发出电波，长翅膀的包裹飞向手机电脑平板 — 路由器把电波一圈圈发到空中，长翅膀的包裹骑着电波，飞向手机、电脑和平板。没有一根线，人人有货收：这就是无线网络。 The router sends radio waves out in rings, and winged parcels ride them to phones, laptops and tablets. No cables at all, yet everyone gets deliveries: that is wireless networking.

离得越远，包裹飞得越吃力吗？Does a longer flight tire the parcels out?

第 2 步：距离和墙都会吃信号Step 2: Distance and walls eat the signal

离得近满格，又远又隔墙只剩1格 — 离路由器越近，信号格越满；每穿一堵墙，信号就弱一截。2.4G 跑得远，5G 跑得快，选哪个看你要啥。 The closer to the router, the fuller the bars; every wall eats another chunk of signal. 2.4G reaches farther, 5G runs faster — pick what you need.

路由器放在家里哪里，信号最好？Where in your home gets the best signal?

第 3 步：放中间，全屋都满格Step 3: Middle spot, full bars everywhere

路由器放角落远处没信号，放中间全屋覆盖 — 路由器塞在门口角落，远的房间就没信号；放在屋子中间，电波均匀散开，间间有份。再设个强密码，陌生人就蹭不走你的包裹。 Stuck in the corner by the door, far rooms go dead; placed in the middle, waves spread evenly to every room. Add a strong password, and strangers can't steal your parcels.

🎮 给全家摆路由器（1 分钟）🎮 Place the router for the whole family (1 minute)

先在实验台试试：距离和墙怎么吃信号。再拖动路由器，让 4 套房子的设备都有 2 格信号。First try the lab bench: see how distance and walls eat the signal. Then drag the router so every device in all 4 homes gets 2 bars.

一句话记住它：无线网络 = 用电波送包裹：放中间、少隔墙、设密码，处处满格。 Remember it in one line: wireless networking delivers parcels by radio wave — middle spot, fewer walls, strong password, full bars everywhere.

电波是看不见的网线，驮着包裹飞向设备Radio waves are invisible cables carrying parcels to every device 越远越弱、穿墙更弱，2.4G 远、5G 快Farther is weaker, walls eat more; 2.4G goes far, 5G goes fast 放中间加设强密码：满格又安全Middle spot plus a strong password: full bars and safe

内容参考 OpenStax 等公开教材，多来源核对 · AI 生成、人工审核 · 发现错误欢迎指正，帮这片叶子长得更好。 Based on OpenStax and other open textbooks, cross-checked across sources · AI-generated, human-reviewed · Spotted a mistake? Tell us — help this leaf grow.